Ignition Advance Curve?

[joeyg1973]

SCR? DCR?

I know the CR stands for Compression Ratio, but I don't know what the S and the D stand for.

Where do I find the head casting? It's a '79 engine all the way though, so it has domed pistons.

I haven't done anything to alter the stock numbers greatly as I plan on putting a supercharger on it at some point and didn't want to shave the head to get more compression. I have what is supposed to be a mild torquer cam and the specs are in the pic below. The pistons were bored .50 over stock and the head and block were both flat so no machining was needed there.

 

[joeyg1973]

I replaced that distributor with an HEI unit and I get:

10 @ 660
13 @ 900
18 @ 1200
23 @ 1500
28 @ 1700
33 @ 2100
38 @ 2900

I used the numbers for Mark's HEI unit and that seems to be just right. 10 degrees seems to be perfect for idle... I have no clue why toyota suggests 7 degrees.

 

[cruiserbrett]

SCR=static compression ratio=mathematical calculation

DCR=dynamic compression ratio=pumping losses/gains affecting the actual amount of air in the cylinder getting compressed. affected by cam timing, pumping efficiency, lift, etc.

 

[Rockiemosley]

“It looks like idle timing is being used for idle stabilization. “ Jim or anybody please, what does this mean exactly? Thank you so much.

 

[Rockiemosley]

I am a bit confused as to wether the above advance curve numbers are generated with or without vacuum advance. When they say “no load” I assume that vacuum advance is connected and they are revving the engine in the driveway so vacuum advance is kicking in. It would be great to have separate numbers with vacuum advance disconnected so that is is possible to discern exactly what the weights and springs are supposed to be doing.